To Vac or Not to Vac

[427 Cobra]

What the website is saying is: the guys who do this IN THEORY say that the airbubbles explode, but this is what leaves the dimples in the mould. These are two different types of chemicals with two very different types of reactions, and viscosities. You may be able to pressurise silicone, but it most likely fail, especially if your mould isn't very deep!